Abstract: In cognitive radio networks, the spectrum handoff performance of secondary users not only relates closely to the communication behavior of primary users, but also related closely to the spectrum sensing accuracy and the spectrum handoff strategies of the secondary users. In this paper, the spectrum handoff schemes that considered with perfect sensing and imperfect sensing are modeled by using the continuous time Markov model, and the affection on the performance of spectrum handoff for different spectrum sensing accuracy is analyzed and compared further. Furthermore, the spectrum handoff strategy based on the channel reservation mechanism is proposed to reduce the forced termination probability of the secondary users effectively in the spectrum handoff process. The numerical results show that the sensing accuracy on the primary signals affects significantly the spectrum handoff performance of secondary users, while the effective spectrum handoff strategy can achieve better performance for spectrum handoff at a lower cost.